This invention relates generally to vehicle rearview mirror systems and, more particularly, to vehicle memory mirror systems.
Vehicle memory mirror systems include at least one, preferably two, electrically operated motors, each of which positions the reflective element with respect to a given axis. By positioning the reflective element about two generally perpendicular axes, the plane of the mirror can be fully positioned. A user-operable switch, such as a joystick or switch pod, is useful to automatically position the mirrors. In a memory mirror system, a monitor device, such as a potentiometer which is coupled to the reflective element, produces a signal indicative of the position of the reflective element with respect to each axis of movement. The signal produced by the monitor device is used in a closed-loop control to allow a controller to reliably position the mirror to particular positions. In this manner, positions of the mirror for different drivers can be stored in memory and retrieved in order to set the mirrors for that driver.
It is generally known in vehicle control systems to provide communication between a vehicle control module and one or more peripheral devices by various communication techniques including digital communications, pulse-width modulation, or other analog communications. It is generally known to apply such communication techniques between a vehicle control module and control modules in each of the exterior mirror assemblies of the vehicle.
A vehicle typically includes at least two mirrors mounted external of the vehicle, both of which are controlled in the same fashion. In order to avoid duplication of hardware, it is common to provide one user-operable input device in order to control both mirrors. That device typically includes manual buttons for manually positioning the mirror, a selector switch to select one of a driver side or a passenger side mirror, and memory set and recall buttons for operating the memory features of the mirror. The user-operable input device is typically associated with a control device in order to multiplex the switches making up the user-operable device and to communicate with each of the reflective elements. In order to reduce the number of wires between the control device and each of the mirrors, various techniques have been proposed to multiplex the signals. One such technique is to provide a bidirectional digital communication link between each of the outside mirrors and a central vehicle-based control. The central vehicle-based control receives switch inputs from the user-operable device. The central control provides digitally encoded commands to each of the mirrors. A control in each of the mirrors includes a memory element in order to store particular mirror settings entered by one or more vehicle operators, a data processor, and a position sensor for the reflective element. The data processor compares feedback signals from the position sensor in order to position the reflective element to a position stored in the memory element. In this manner, the central vehicle-based control is greatly simplified and does not need to include a memory function. The only requirement of the control vehicle-based control is that it is capable of encoding data signals.
As disclosed in commonly assigned U.S. Pat. No. 5,798,575 issued to Desmond J. O""Farrell, Roger L. Veldman and Kenneth Schofield for a VEHICLE MIRROR DIGITAL NETWORK AND DYNAMICALLY INTERACTIVE MIRROR SYSTEM, the disclosure of which is hereby incorporated herein by reference, vehicles are increasingly being equipped with serial data communication networks. Such networks include a bidirectional serial multiplex communication link over a bus among a plurality of control modules, each containing a microprocessor or microcomputer. While such serial data communication network could be utilized to provide a communication link between the central processor in each of the mirror assemblies, the protocol of the system provides that higher priority messages are communicated without delay while lower priority messages would be considered lower priority messages, the serial data communication network may often introduce delays in positioning of the reflective elements. Furthermore, the serial data communication networks are relatively complicated with strict protocol definitions and rigorous hardware requirements.
It would be desirable to provide a vehicle memory mirror system which would incorporate the data processing functions, such as memory storage of multiple mirror positions and the like, in a central control remote from at least one of the mirror assemblies while utilizing a low-wire-count interface between the central control and the mirror assembly.
It would be desirable to provide two or more speeds of operation of a mirror-positioning system. When the user is manually positioning the mirror, it is desirable to move the mirror at a relatively slow rate in order to avoid overshoot of the desired setting under the control of the operator. However, when the mirror is being repositioned to a fixed setting by the processor, it is desirable for the mirror to move at a faster rate. This is particularly desirable because memory mirrors also include a downward tilt setting which is a permanent setting invoked whenever the vehicle is placed in reverse gear. This rotates the mirrors downwardly in order to provide a back-up aid to the driver who is typically interested in the area around the vehicle, rather than in the distance behind the vehicle, when making difficult parking maneuvers and the like. In order to be useful, it is desirable that the mirrors switch to the downward tilt position immediately upon the vehicle being placed in reverse gear in order to provide immediate assistance to the operator.
According to an aspect of the invention, a vehicle mirror system includes a vehicle mirror assembly and a control module. The vehicle mirror assembly includes a reflective element, a motor for positioning the reflective element about an axis, a monitor for monitoring the position of the reflective element with respect to the axis, and a mirror-based control operatively connected with the motor and the monitor in order to position the reflective element at a particular position with respect to the axis. The control module is interconnected with the mirror-based control by an analog interface. The control module includes a processor for providing analog signals on the analog interface indicative of a desired position of the reflective element with respect to the axis. The mirror-based control includes a positioning controller circuit which compares analog signals on the analog interface with a signal produced by the monitor in order to generate signals to operate the motor and thereby position the reflective element at the desired position. The vehicle mirror assembly includes at least one accessory. The mirror-based control either decodes analog signals on the analog interface or encodes analog signals on the analog interface, or both, in order to selectively operate the at least one accessory. Examples of such mirror-based accessories include a turn signal light, a stop signal light, a heater, a security light, a garage door opener, a power-fold mechanism, and the like.
Preferably, the positioning controller is a servo-controller circuit. The use of a servo-controller circuit provides a reliable analog circuit which is capable of responding to the analog signals formatted on the analog interface in order to reliably position the reflective element at its desired final position. Advantageously, the servo-controller circuit can be implemented in an application-specific-integrated-circuit for low-cost, high-volume production. Alternatively, other forms of positioning controllers may be used.
According to another aspect of the invention, a vehicle memory mirror system includes a vehicle mirror assembly and a control module. The vehicle mirror assembly includes a reflective element, a motor for positioning the reflective element upon an axis, a monitor for monitoring the position of the reflective element with respect to the axis, and a mirror-based control operatively connected with the motor and the monitor in order to position the reflective element at a particular position with respect to the axis. The control module is interconnected with the mirror-based control by an interface. The control module includes a processor for providing analog signals on the interface indicative of a desired position of the reflective element with respect to the axis. The processor controls the speed at which the reflective element moves toward a terminal position by formatting signals which each represent an incremental movement of the reflective element with respect to the axis. In this manner, should the processor wish to move the reflective element to a final position at a high rate of speed, the processor formats signals representing the final position of the reflective element or large incremental movement signals. The vehicle-based control will then respond by moving the reflective element at a speed limited only by the hardware of the vehicle mirror assembly. If, however, the control module intends to move the reflective element at a slower speed, the processor formats a series of analog signals, each of which represents smaller incremental movement of the reflective element. In this manner, the frequency with which the incremental move commands are issued and the amount of movement represented by each command allows the control module to regulate the speed of movement of the reflective element. In this manner, the reflective element can be moved to its final position at a high rate of speed, for example, when it is being positioned from a retrieved memory setting. The control module can move the reflective element at a slower rate of speed, for example, in response to commands manually entered by the driver, in order to avoid overshoot.
According to yet another aspect of the invention, a vehicle memory mirror system includes first and second vehicle mirror assemblies. Each assembly includes a reflective element, a motor for positioning the reflective element about an axis, a monitor for monitoring the position of the reflective element with respect to the axis and a mirror-based control operatively connected with the motor and the monitor in order to position the reflective element at a particular position with respect to the axis. One of the mirror-based controls includes a computer and memory for storing preselected positions of the reflective elements of both of the mirror assemblies. The other mirror-based control is interconnected with the one mirror-based control by an interface. The other mirror-based control responds to signals output to the interface by the one mirror-based control indicative of a desired position of the reflective element associated with the other mirror-based control and a signal produced by the associated monitor. The other mirror-based control operates the associated motor in order to position the associated reflective element to the desired position. This configuration provides a vehicle mirror network which is exceptionally effective and economical.
These and other objects, advantages, and features of this invention will become apparent upon review of the following specification in conjunction with the drawings.